The present invention relates to an electric power steering apparatus or system, which is provided with an electric motor as a drive source and is configured to apply an assist steering effort to a steering mechanism of a motor vehicle, and relates to a controller for such a power steering apparatus.
Japanese Patent Application Publication 2011-080841, which corresponds to United States Patent Application Publication 2011/0080160, discloses an electric power steering apparatus that is provided with an electric motor, and is configured to sense a steering angle of a steering wheel from its neutral position, and cause the electric motor to apply an assist steering effort to a steering mechanism of a motor vehicle on a basis of the sensed steering angle. The steering angle of the steering wheel from the neutral position is measured with a torque sensor or steering angle sensor.